Rod seal for shock absorber



E. F. RossMAN 'Y 2,943,711 Ron SEAL FOR SHOCK ABSORBER Jjuly'vs, 1960;

V lFiled Sept."15, 1958 INV ENTOR. Edw/h F. Rossman.

BY Chg.

vl I v J JH A IIIII Hisu At United States Patent 2,943,711 i ROD SEALFOR SHOCK ABSORBER Edwin F. Rossman, Dayton, Ohio, assignor to GeneralMotors Corporation, Detroit, Mich., a corporation of Delaware FiledSept. 15, 1958, Ser. No. 761,101 3 Claims. (Cl. 18S-100) This inventionrelates to a direct acting shock absorber and particularly to a sealstructure at the end of the shock absorber at which the actuating rodprojects from the shock absorber cylinder.

When installing shock absorbers on equipment, it is important that theconnections of the shock absorber with the equipment be properly alignedthat transverse forces will be held to a minimum between the slidingparts of the shock absorber. This is particularly true of the direct`acting type shock absorber wherein the actuating rod extends axiallyfrom the cylinder of the shock absorber. lIn shock absorbers of thistype, axial misalignment of the connections on the vehicle by which theshock absorber rod is connected to the vehicle at one end and the shockabsorber cylinder is connected to the vehicle at the other end, isparticularly troublesome because axial misalignment of the connectionson the vehicle result in a transverse thrust of the shock absorber rodrelative to the shock absorber cylinder, which is particularly Ibad onthe seal structure for the rod which cannot stand any substantial amountof transverse misalignment thrust without shortening the life of theseal and causing it to leak. ltis, therefore, an object of Ithisinvention to provide a seal structure around the rod of the shockabsorber at the end of the shock absorber through which the rod extendsthat is capable of absorbing misalignment thrust or transverse thrust,the seal structure being radially shiftable within a seal cavityprovided for the seal structure so that the seal structure can alignitself axially with the shock absorber rod, regardless of transversethrust or radial thrust of the ro relative Ito the seal structure. A

It is another object of this invention to provide a seal structure forthe rod end of a direct acting shock absorber wherein the seal structureiloats radially within a seal cavity provided in the shock absorberstructure, the seal structure including an annular body member that issupported on the rod of the shock absorber and which is capable ofmoving radially with the rod of the shock absorber when misalignmenttransverse thrusts are applied to the rod of the shock absorber. Inaddition, a seal member is provided between the seal `body and a wall ofthe seal cavity in the shock absorber body that allows the seal body tomove radially relative to the body of the shock absorber when the shockabsorber rod thrusts radially against the seal body.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

In the drawings:

Fig. l is a longitudinal cross-sectional view of a direct acting shockabsorber incorporating the seal structure of this invention.

Fig. 2 is a longitudinal cross-sectional view of 'a portion of a shockabsorber illustrating a modified construction of a seal structure forthe rod of the shock absorber.

As illustrated in Fig. l, the shock absorber consists of a cylinderreceiving a shock absorber piston 11 that is carried on one end of theactuating rod 12, the piston 11 being positioned within the cylinder 10for reciprocation in aconventional manner.

One end of the cylinder 11 is closed by an end wall 13 incorporating afoot valve 15 that allows hydraulic iluid to be displaced from thechamber 16 between the piston 11 and the wall 13 by movement of thepiston toward the foot valve 15, and allows free ow of fluid back intothe chamber 16 when the piston 11 moves away from the foot valve 15.

The opposite end of the cylinder- 10 is closed by an end wall 18 thathas a bearing bushing 19 that supports and slidably receives theactuating rod 12, the actuating rod 12 extending from the cylinder 10through the end wall 18 for attachment to one part of a vehicle.

The shock absorber cylinder 10 is enclosed by a cylindrical housing 20that is spaced `from the cylinder 10 to provide an oil reservoir chamber21. The end wall 13 containing the foot valve 1S engages theI end wall22 of the housing 2), and chamber means 23 is provided to allowhydraulic fluid to ow between the chamber 16 and the reservoir 21 in amanner previously referred to.

The housing 20 threadedly receives an end cap closure member 25, thethreads 26 being provided to retain the end cap member 25 within theIleft-hand end of the housing 20, as shown in Fig. 1. An 0 ring seal v27between the member 25 and the housing 20 prevents loss of hy-draulic uidfrom the reservoir chamber 21.

The end cap member 25 engages the end Wall 18 of the shock absorbercylinder 10 and thereby retains the shock absorber cylinder in positionbetween the end cap member 25 and the end wall 22 of the housing 20.

The shock absorber piston 11 is provided with suitable valving to allowhydraulic fluid to ow from the chamber 28 into the chamber 16 onleft-hand movement of the piston 11, and to provide for ow of hydrauliciluid from the chamber 16 back into the chamber 28 on righthand movementof piston 11.

From the foregoing description, it will be apparent that the shockabsorber may be of a more or less conventional type, direct acting shockabsorber.

vThe rod seal structure lat the left-hand end of the shock absorber, asshown in Fig. l, is located within a recess 30 that provides a sealchamber 31 in the end cap member 25 on the outboard side of the end wall18.

The seal structure consists of an annular body member 32 that cooperateswith an annular body member 33 to form an annular recess or chamber 34.The body members 32 and 33 are supported upon the outer periphery of theactuating rod 12.

The chamber 34 contains an annular seal ring 35 that is preferably aTeon ring, which is a ring of polytetr-a- Iiluoroethylene material madeby E. I. du Pont de Nemours & Co. The polytetrauoroethylene seal ring 35is backed up by an annular `ring 36 of elastic rubberlike material,preferably in the form of an O ring.

'l The seal elements just described are carried by the shock absorberrod and can move radially with the rod whenever the rod has transversethrust applied to it. The seal body member 32 has a radially disposedannular face 40 that is in spaced parallel relation to a correspondingradially disposed annular face 41 on the end cap member 25. An annularseal ring 42 of elastic rubber-like material, preferably an O ring, isplaced between these parallel faces 40 and 41 to seal there4 against. -Acompression spring 43 is placed between the seal body member 32 and theend Wall 18 of the shock absorber cylinder 1G to apply an axiallydirected pressure upon the rings 36 and 42 to eect sealing engagementwith their respectively engaged surfaces. The ring 36 also appliespressure on the Tetlon or polytetraiiuoroethylene seal ring 35 to insurepositive engagement with the ring 35 with the periphery of the rod 12and thereby seal upon the rod. Y

It will be apparent from the structural arrangement of the parts of theseal just described that when transverse force is applied to the rod 12,tending to move the rod in a radial direction, the rubber-like ring 42will allow the. sealbodymember;32.to;move:i1r a radiaLdireetion.Y andthereby .float ,within the. seal chambenl :so l that. thesealstructurewill, at. all1tin1es.be. concentric withwthenrodfll, andiwill.be relieved off alhtransverse` thrustss. The springymember 43,acts...similarly; tothe. member 42 in., allowing. radial.- movement.ofthe seal. structure since the spring hasalaterahexibility.that will.allow. for. acceptance of=a 4'considerable.,.amount t of 4radialmovement .f ott the member.Y 33rela1ive A tothee end. wall i 18..YPassages 1:9 vin the .wall liprovide-ior tluidcconnecf,tin.,betweenv.chamber 31 and reservoir e 21,10, A`avoid rpvresf A suredevelopment-,in r.chairmen-3l, the. seal .beinggaflow pressureseal.;`

In:.Fig.l-, 2. there :is :illustratedV a `slightly modified 'f form of:a seal structure, thetshockabsorber in `l*`.ig:.2 including.,y ashocln, absorber., cylindert 59 ,-enclosed'rwithin sa z. hous..A ing..51 that .is,..spaced 4V.from the cylindento. provide..for.: anoilrreservoirlSZ.. Thel cylinder .S11-is closedzbyythe. vend wall 53.andA the actuatingrod-,Sdis received/ by y,the bear-y ing sleeve, 55.yin the. endtwally. 53, -and :projects: from the:shocktabsorberzthroughthe endtwall,

An :enclosure Acapil yisthreaderlly receivedby 'the-house inggSltby'wmeansso the threadconnectionalrand isrprof. -1 vided .-with avchamber- 62 rarrangedzas as. seal chamber:n for the sealstructurefortherod 54.

The` seal-structure consists. of. an. annulargbodyniemherz 65 that hasfanlannular recess zformedl Abytheepalrallel Vhanged ,portionszof thebodyA member;thatfengageethe.; periphery fof .the rodS y to:support the,body member- 65 a (mathe,:rod-.54.2 Ane-annular seal ielementz'lisfreceived within. ,fthe @recess 166: in theybody member., 65,'.thisnseal..

member 67 Vbeing,intheforrn .ofa two-.turn spiralgthatz.

is;-.threadedtthrough the. openingin-the seal .body 6S1be:foreff-the-fseal body' ist placedzomthe.- rod. 54.2. The; sealz. element67 is made of Teflon, thatljs apolytetrauor ethylene;,materia1,.andsisebaclredA upiby.axr;annular;'ring of;elastic.rubber-likeimaterial68-r preferably farro.. rin`g.;,

When the seal structurefjustzdescribed-is placedzon'thee rod ;54,ithe;.annular:ringr68zis deformed and ,displaced by its:engagementawithdh'e rod-.54.z`and byrits` confine,- ment\vithin;the,reeess1,66\, so:that itxsealingly'engages-the;A peripheryofntherrod Srandxalsof-appliesfaxiallyzdirected pressure zon the.`polytetrauoroethylene ring 167 to v-insure sealing =engagement 'of-:thisring :with theperipheral surf face of the-rod'54.

The=-seal body*65 isprovided `with-a radiat flange 70:Y

that has a radially disposed surface "7lpositionedlin parallel relationto'th`e5radially disposed .surface 72of a i walliothe chamber 62.l An`annular ring 73 `of elastic.. rubber-like materialiis". .placedibetweenthe parallel surfaces:.71 andi72. so.that .when .the..member.74tisthreaded. into the member. 75.v withvthe; wallrtg engaging-a=p9lyyr=tetrauoroethylene ring, 77, the ring 73 .is placed undercompression,,and;deformedto asuicient extent .to provide: axiallydirectednpressurelon.. the ring ,V7 7 i and-.eect: sealingengagernentbetween thelmemberc74 and ,the lseal body, 65A Fronntheforegoing-:description inl Figsv2; it"-` wilLbeL-apparent thanwith'theYseal body member 65 fsup-.i ported 'upon the rod. 54,1- it isyfloatinglyy supported#betweenm thesipolytetrauoroethylene-s ringf- 77and th'eering` 73;; sothat r'anyfA radial movement Y of the rod 54 fwillcarrythe seal b'odyj65 with the rod and thereby/"relieve the seal:vstructureof all radially ontransverselyjdirectedthi'usts.

Passages 80 in the Wal'L53 provide for. lluid'connection between'-chamberSLand reservoir52 to avoid ,pressure development in chamber 81and theseallcharnher, the,Y sealbeing a low-pressure seal.`

While the embodiments ofi. the. present invention as f herein disclosedconstitute a preferred 1o1' n1,itis.`to` beev understoodvthatrother.,forms might ,-beeadoptedt.

What is claimed is as follows:

l. In a shock absorber, a'rodseal vfor the same, comprising incombination, a cylinder having a piston reciprocable therein, saidpiston being attached on one end of an actuating rod extending'throughone end of said cylinder, ,saidncylindenhying an` end wall closing therod end 'ofsaid `cylindr and providing a bearing sup-, p ortfr'saidrodin'whichit isslidablefan'end1capmem= ber on said^'rodend"ofsaidcylinder onth`e,outb`oard side of said.,endwall.coop,erating.withsaid end wall`to provide an annular seal'chamber around 'sadrod on theoutboard side of\'saidend Wall through which said rod extends, anannular seal body member Within said chamber: andxonzsaid:.rod;saidabodyrmembenhaving an 1 annu1a`r;recess:1radia11y adjacent:saidsrod y'and formingiwith: :said-rod:` axseal'cont-irringrchamber,.azsealf structures positioned within saidconfining chamber `andsconsistingrl of am annular-,fringeoff:polytetrauoroethylene. held under compressionfawithin-z l said.-chamber: by lannannular.v ring of l elastic :rubber-like material:`Wh'erebyito .'sealfupon said rod; said body membenhavinga radiallydisposed planar flangesurface firr spacedparallel relationship to ra.corresponding radially: disposedtannularf-planan face .on said'endLeap," and an; elastici. rubber-like :seal l. memberv betweenA said'angmsurfacea'and said face fseali-ngly engaging-both lfaees 1andnproviding:forffrelativeemovement therebetween:-

2:1. Ae' rodfxseakfori'asshoekaabsorber fincluding the-combinati'onsetforthsinrrclaim llwhereinf-,said seal member" bet-Weenrsaid'lainge'fsurfacef-and said `face'- comprises' an annularzoringr 3.1 Inrashock absorber;raarodisealfforfthesame; com-' prisings in combinatiorn7a. cylinder' Ahaving af pistom-re-I ciprocable.':thereim Y saidpistonf-b`eingl attached 'l onl oneL end offanaactuating': rodfextending through one endfof 'i said cylinder', said cylinder having;yan: endiwall closing f theurod end fof-i said'- cylinder` andprovidin'g' a1 bearingl support :for said rod-fin lwhehr-ittisi slidble;an'end'capI member on .fsaid irodf' endfof said cylinder "ontheoutboard;'sdefoff'saida `end1 `'wall iandfth'l'ough'v which'said rodi extends..land cooperating-Withisaidv'fend:iwall to -provide s an: lannular` sealchamber around I:said: rod 1 on" the-lout#- boardaside'fofsaidendflwall;an 1 annular-seallbody .mern-v v berr'withinfsaidf-chamber-and'onfsaidrod; saidY body-member having an annular axially extendingopen-endedrecess fradiallyf-:adjacent-s aid rod, aY sealifstructure in saidrecessr.v comprising a-ring of-fpolytetrauoroethylene en`V gaged byafcompressibledannularring of f elastic rubber-y likefmater-ial-toplaceecornpressionf pressure onsaid 'poly' tet-raoroethylene Xring,j an7annulrfcompressio'n ring car' rie'dcon said rod.=and= having-fan endAportion slidablefwithnl saideannular recess-'land engaging' saidIrubber-likeeringL said body memberl having a: radiallydisposedl planaran-J nular facefinVl spaced parallel-@relationshipfto-a corredsponding:radiallyfdisposed planarA annular-fa`ee l=orr said endicap;W an annularresilientseal"4 member of elastic' rubberelikey material? between saidfaces andeengagirigjl both-l saidffaces--and@ providing" for" radial'displacement therebetween, a compressionzspring-jbetweenesaid'cornepression: ring Landsaid 'endvwall 'to' apply/ axially 'directedpressurefonl =both"1 said 'seal members concurrently" to* ef-'fectfseali'ng l engagement thereof with* their respectively engagedsurfacess References Cited in the file of this 'patent'UNITEDQSTATESzPATBNFIS:

621,817 Hopkins Marr281899f 965,688? Glai'ri July 26; 1910 l,7.l5;4831Wallierv Iune'4; 1929 1,966,310@ Padgett; .TulyflOIv 1934 2;7.49;193`Trauben June-S 1956 2,857,1821-lr- Mncusi Oct-21,- 1958*FOREIGN-PATENTS:

27,527 Great Aprx23 1914".

